Gel coating method and apparatus

ABSTRACT

A gel coating method comprising making a mold ( 27 ), which has both a gelatinizer impermeability or a slight gelatinizer impermeability and a hardening agent permeability, retain a hardening agent ( 26 ) thereon beforehand by immersing the mold ( 27 ) in the hardening agent ( 26 ) and taking out the mold ( 27 ) therefrom, placing a gelatinizer ( 30 ) and an object to be sealed ( 9 ) in the resultant mold ( 27 ), allowing the hardening agent ( 26 ) to permeate through the mold ( 27 ) as a whole by immersing the mold in the hardening agent ( 26 ) again, and uniformly hardening the gelatinizer ( 30 ), which is around the object to be sealed ( 9 ), from the portion thereof which contacts the mold ( 27 ), whereby the object to be sealed ( 9 ) is rendered easily removable as gel-coated object ( 9   a ) from the mold ( 27 ).

This application is the U.S. National Phase under 35 U.S.C. §371 ofInternational Application PCT/JP99/02203, filed Apr. 23, 1999. TheInternational Application was not published under PCT Article 21(2) inEnglish.

TECHNICAL FIELD

The present invention relates to a method and apparatus for coating witha gelatinizer an object having a growth ability such as a seed, a cellpiece or the like having a germinating or rooting ability, and moreparticularly to a gel coating method and apparatus also capable ofgel-coating a heavy seed or a seed having a poor germinating ability.

BACKGROUND ART

Conventionally, a coated object obtained by coating such an object to besealed as a seed, a cell piece or the like with a macromolecular gelcontaining nutriments, medicament and the like and being elastic(hereinafter generically, the object to be sealed is called a “seed” andthe coated object is called a “coated seed”; and that is, hereinafter incase of referring to a “seed” or a “coated seed”, the “seed” means notonly a seed but also any object having a growth ability such as a cellpiece having a germinating or rooting ability) is known. The coated seedhas many advantages such as that the coated seed is effective to protectthe seed from being eaten by animals or sterilize the seed, that itmakes it easy to handle the seed by making the seed larger in graindiameter and thereby makes its seeding operation more efficient, andthat furthermore it enables to improve its germination rate due toabsorbing nutriments in the macromolecular gel.

By the way, as a typical method for automatically manufacturingabove-mentioned coated seed, there are a double-cylinder nozzle methodand a mold method.

First, a double-cylinder nozzle method is explained with reference toFIG. 7. This method slightly pressurizes the inside of a gelaccommodating portion 3 of a gel accommodating block 2 into which agelatinizer is supplied from a gelatinizer tank, not shown, by means ofan air cylinder, not shown, fills a passage 4 of the gel accommodatingportion 3 and a space 5 communicating with the passage 4 with thegelatinizer as well as raises the pressure inside the space 5, andthereby moves upwardly a cylindrical plunger 6 mounted so as to be movedup and down inside of a nozzle block 1 against the elastic force of acoil spring 7 provided on the top end of the plunger 6, and slightlyopens a valve 8 and discharges the gelatinizer to form a thin film ofthe gelatinizer on the lower end of the valve 8. After that, this methodthrows a seed 9 into a passage 6 a of above-mentioned plunger 6 andmakes above-mentioned thin film hold the seed 9 and then furtherpressurizes the inside of above-mentioned gel accommodating portion 3 toraise the internal pressure of the space 5, and thereuponabove-mentioned valve 8 is greatly opened and a great amount ofgelatinizer is discharged and the gelatinizer wraps the seed 9 in it incooperation with above-mentioned film, and when a grain-shapedgel-coated seed 9 a is formed thereby, the gel-coated seed 9 a isdropped due to its own weight into an lower hardening tank, not shown,containing a hardening agent. The gel part of the gel-coated seed 9 a ishardened while being conveyed through the hardening tank, and thehardening agent is washed away in a water-washing portion to form aproduct.

However, such a double-cylinder nozzle method has a disadvantage that incase of gel-coating a heavy seed such as corn, bean and the like, itcannot be gel-coated in some cases because above-mentioned thin film ofthe gelatinizer is broken by the shock of dropping of the seed. In orderto prevent the break of the thin film, it is conceivable to raise theviscosity of the gelatinizer, but a problem has occurred that since thegel coating layer is made harder by doing so, the seed is difficult togerminate. Moreover, there has been a problem that in case ofgel-coating a seed having a poor germinating ability, it is necessary tomake the viscosity of the gelatinizer as low as possible in order toobtain a sufficiently high germinating ability, but in a double-cylindernozzle method a spreadable viscosity of the thin film has the lowerlimit which has sometimes made a gel-coating process impossible.Furthermore, when above-mentioned gel-coated seed 9 a is dropped due toits own weight into a lower hardening tank, a hardening agent spatteredonto the lower end of above-mentioned nozzle block 1 has sometimes madea gel-coating process impossible.

Next, a mold method is a method which throws a seed into a mold whoseinner face is spherical and at the same time fills the mold with agelatinizer and a hardening agent, and takes out the gel-coated seedfrom the mold after it has been hardened. In this case, since thismethod does not use a stretched thin film of a gelatinizer to support aseed differently from above-mentioned double-cylinder nozzle method, ithas an advantage that the gelatinizer does not need to be made higher inviscosity in order to enforce the seed supporting ability and itsviscosity can be freely set to an adequate degree to provide a highefficiency of germination. However, there has been a problem that sincea gelatinizer is difficult to be released from a mold, a seed cannot becoated in the shape of a sphere in some cases, and in the worst case agel-coated seed cannot be released from the mold. Further, there hasbeen a problem that this method is disadvantageous in work efficiencydue to necessity of an operation of removing a hardening agent or agelatinizer stuck to a mold each time a gel-coating process isperformed.

DISCLOSURE OF THE INVENTION

The present invention provides a gel coating method obtained byimproving above-mentioned mold method, which gel coating method injectsa gelatinizer and an object to be sealed into a mold having both agelatinizer impermeability or a slight gelatinizer impermeability and ahardening agent permeability, allows a hardening agent to permeatethroughout the mold by immersing the mold in the hardening agent, anduniformly hardens the gelatinizer, which is around above-mentionedobject to be sealed, from its contacting part with the mold, and therebyrenders the object to be sealed easily removable as a gel-coated objectfrom the mold. This method can securely coat with gel even a heavyobject to be sealed or an object to be sealed having a poor germinatingability since it does not support an object to be sealed with a thinfilm of a gelatinizer. Moreover, since hardening of a gelatinizerproceeds in order from the contacting part with a mold, no unhardenedgelatinizer is stuck to the inner face of the mold and the moldreleasability of a gel-coated object is remarkably improved incomparison with a conventional mold method, and it is possible also tosuppress remaining of a gelatinizer in a mold.

Moreover, since a thin hardened layer of a gelatinizer is formedbeforehand at a contacting part between a gelatinizer and a mold bymaking above-mentioned mold retain the hardening agent through immersingthe mold in the hardening agent and taking out the mold before injectingthe gelatinizer and an object to be sealed into the mold, it is possibleto further improve a gel-coated object in mold releasability.

The inner face of a mold used in above-mentioned method is composed of asemispherical portion projecting downward and a cylindrical portion setupright on the spherical portion, and the whole depth from the top endof the cylindrical portion to the bottom end of the semisphericalportion is made equal to or greater than the diameter of above-mentionedsemispherical portion, and therefore a gel-coated object can be surelymade sphere-shaped.

Further, in case of using a mold having a slight gelatinizerimpermeability as above-mentioned mold, since one that is composed suchthat it takes a time of one or more seconds for a gelatinizer topermeate through the mold, it is possible to completely prevent thegelatinizer injected into the mold from leaking out before immersing themold in a hardening agent.

Moreover, it is acceptable also to use a mold made of an elasticmaterial as above-mentioned mold, transform the mold by pressing itslower part from below, and extrude a gel-coated object in the mold intothe hardening agent, and then restore the mold to its original shape,and in this case it is possible to more quickly release the gel-coatedobject from the mold by the mechanical extrusion in addition toabove-mentioned hardening.

And, this method limits the thickness of a hardened layer formed byreaction of a gelatinizer injected into above-mentioned mold upon thehardening agent retained beforehand in the mold to 20% or less of theradius of a semispherical portion forming the lower part of the mold andprojecting downward. Therefore, since the gel-coated object proceeds inglobing by a surface tension as suspending in the hardening agent, it ispossible to make the gel-coated object more completely sphere-shaped.

And the present invention provides a gel coating apparatus suitable forusing the gel coating method. That is, a gel coating apparatus accordingto the present invention comprises a mold which has both a gelatinizerimpermeability or a slight gelatinizer impermeability and a hardeningagent permeability, an object to be sealed feeding means for throwing aspecific number of objects to be sealed into the mold, a gelatinizerfeeding means for discharging an adequate amount of gelatinizer forapplying to the object to be sealed, a hardening tank which is disposedbelow the gelatinizer feeding means and the object to be sealed feedingmeans and is filled with a hardening agent, a mold immersing means whichcan consecutively immerse molds in the hardening tank and take out themolds from the tank, and a gel-coated object collecting means for takingout a gel-coated object which is released from the mold and suspends inthe hardening agent from the hardening tank, which gel coating apparatusimmerses the mold having a gelatinizer and an object to be sealedinjected in it by the object to be sealed feeding means and thegelatinizer feeding means in a hardening agent inside the hardening tankand thereby makes the hardening agent permeate throughout the mold toharden the surface of the gelatinizer in the mold and releases thegel-coated object from the mold.

According to this apparatus composition, a gelatinizer and an object tobe sealed are injected into a mold respectively by an object to besealed feeding means and a gelatinizer feeding means, and the mold isimmersed in a hardening tank and is taken out from the tank, and at thistime, since the gelatinizer in the mold starts to be hardened uniformlyfrom the contacting part with the mold by the hardening agent which haspermeated throughout the mold, the gel-coated object is easily releasedfrom the mold and is collected by a gel-coated object collecting means.Since this apparatus does not have a structure which holds an object tobe sealed with a thin film of a gelatinizer, it can surely gel-coat evena heavy object to be sealed or an object to be sealed having a poorgerminating ability, and further since hardening of a gelatinizerproceeds in order from the contacting part with the mold, no unhardenedgelatinizer is stuck to the inner face of the mold and the moldreleasability of a gel-coated object is remarkably improved and theremaining of a gelatinizer in the mold can be also suppressed.

The gel-coated collecting means comprises two pulleys arranged in thelongitudinal direction, a belt wound around the pulleys, and a pluralityof paddles stood upright on the outer face of the belt, and the paddlesare moved in the hardening tank as one body with the belt by rotation ofthe pulleys to generate a circulating flow, transfer gel-coated objectssuspending in the liquid surface, and scoop up and discharge agel-coated object transferred to the terminal to the outside. Accordingto this composition, since generation of a circulating flow fortransferring gel-coated objects suspending and discharge of gel-coatedobjects which have been hardened can be performed by a single meanshaving a simple structure, it is possible to attain manufacturing costreduction and space saving by reduction of the number of devices.

And the mold immersing means comprises an upper pulley arranged near thegelatinizer feeding means and the object to be sealed feeding means andnear the liquid surface of the hardening agent in the hardening tank, alower pulley arranged distantly from the upper pulley and deeply in thehardening agent, and a mold built-in belt wound around the upper andlower pulleys, and the mold built-in belt has a plurality of molds whoseopenings face outward embedded in it. According to this composition,since it is possible to consecutively perform a gel coating process, theefficiency of work can be remarkably improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a main part of a gel coating apparatusaccording to the present invention, showing a gel coating methodaccording to the present invention;

FIG. 2 shows explanatory diagrams showing a procedure of a gel coatingprocess in the main part of the gel coating apparatus, and a) is anexplanatory diagram showing a state where a mold is immersed in ahardening agent in advance, b) is an explanatory diagram showing a statewhere a seed and a gelatinizer are injected in a mold, c) is anexplanatory diagram showing a state where a hardening agent haspermeated into the inside of the mold, and d) is an explanatory diagramshowing a state where a gel-coated seed has been released from the mold;

FIG. 3 is a side sectional view of a mold;

FIG. 4 is a side sectional view of a mold having a gelatinizer and aseed injected in it;

FIG. 5 is a side view, partially in cross-section, showing a roughcomposition of a first embodiment of a gel coating apparatus accordingto the present invention;

FIG. 6 is a side view, partially in cross-section, showing a roughcomposition of a second embodiment of the same;

FIG. 7 is a side view, partially in cross-section, of a main part of aconventional gel coating apparatus using a double-cylinder nozzlemethod.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, embodiments of the present invention are described with referenceto the drawings. The present invention is not limited to theseembodiments, but covers widely the whole scope of a technical ideareally intended by the present invention which will be made apparentfrom the whole description of this specification and the accompanyingdrawings.

First, a main part of a gel coating apparatus adopting an improved moldmethod of the present invention and an outline of a gel coating methodperformed in the main part of the apparatus are described with referenceto FIGS. 1 and 2. As shown in b) of FIG. 2, a gelatinizer 30 and a seed9 being an object to be sealed are injected into a mold 27 according tothe present invention having both a gelatinizer impermeability or aslight gelatinizer impermeability and a hardening agent permeability. Asshown in c) of FIG. 2, when the mold 27 is immersed in a liquidhardening agent 26 filling a hardening tank 18, the hardening agent 26starts permeating into the inside of the mold 27 not only from the upperopening 27 a of the mold 27 but also through the wall 27 b of the sideand the bottom. When the peripheral part of a gel-coated seed 9 a ishardened and contracted by the hardening agent, the hardened outermostface is released from the inner wall of the mold 27. The releasedgel-coated seed 9 a is made grain-shaped by action of a surface tensionand is raised to the surface of the hardening agent 26 by a buoyantforce, as shown in d) of FIG. 2, due to a small specific gravity of thegel portion.

By immersing the mold 27 in the hardening agent 26, taking out the mold27 from the hardening agent and making the mold 27 retain the hardeningagent 26 in it in advance, as shown in a) of FIG. 2, before injectingthe gelatinizer 30 and a seed 9 being an object to be sealed into themold 27, the injected gelatinizer 30 and the retained hardening agent 26react upon each other, and a thin hardened layer of the gelatinizer isformed in the contacting part with the inner face of the mold andthereby the releasability of the gel-coated seed 9 a from the inner faceof the mold 27 can be more improved.

Since a gel coating method according to the present invention utilizes amold method and originally does not need to support a seed 9 with thethin film of the gelatinizer 30 differently from the double-cylindernozzle method using the apparatus shown in FIG. 7, this method cangreatly expand an applicable range of the weight of a seed 9 or theviscosity of a gelatinizer 30, and further since the hardening agent 26permeates into the inside of the mold 27 through the whole mold wall andhardens the gelatinizer 30 in order from the contacting part with themold 27, the mold releasability of a gel-coated seed 9 a is remarkablyimproved in comparison with the prior art mold method and remaining ofthe gelatinizer 30 on the inner face of the mold 27 can be alsoprevented.

Next, the shape and characteristics of a mold 27 used in the presentinvention are described with reference to FIGS. 3 and 4. Although theshape of the inner face of the mold 27 is not particularly limited, asshown in FIG. 3 the mold is preferably composed of a semisphericalportion 27 d projecting downward and a cylindrical portion 27 c setupright on the semispherical portion 27 d in order to form a sphericalgel-coated seed 9 a. Particularly, the whole depth 33 from the top ofthe cylindrical portion 27 c to the bottom of the semispherical portion27 d is preferably secured to be double or more than the radius 32 ofthe semispherical portion, namely, equal to or greater than the diameterof it. The reason is that when the whole depth 33 is shallower than thediameter, a soft gel-coated seed 9 a projects from the top of the mold27 on the way of hardening and is liable to transform due to a fact thatthe projecting portion receives the resistance of liquid flow and thelike and further it is not possible to secure a necessary amount ofgelatinizer 30 for globing.

And the gelatinizer 30 in the mold 27 needs to be impermeable orslightly impermeable in permeability, and the reason is that thegelatinizer 30 injected into the mold 27 is prevented from leaking out.In case of a slight impermeability, allowing for a time from whenfeeding the gelatinizer 30 into the mold 27 to when immersing the mold27 in the hardening agent 26, it takes preferably one or more secondsfor the gelatinizer 30 to permeate through the mold 27. The reason isthat if it is shorter than this, there is the possibility that thegelatinizer 30 fed in the mold 27 leaks out before the mold 27 isimmersed in the hardening tank 18.

Further, the mold 27 is preferably an elastic body which is easilytransformed by being pressed from downward to press out a gel-coatedseed 9 a being inside the mold 27 from the mold 27 and then can beimmediately restored to its original shape, and thereby a mechanicalpressing-out force can be added to a buoyant force and the moldreleasability can be more improved.

And in case of immersing the mold 27 in the hardening agent 26, takingout the mold 27 from the hardening agent 26 and retaining the hardeningagent in the mold 27 in advance, it is preferable to limit the thickness34 of a hardened layer 31 of the gelatinizer 30 formed by reacting uponthe hardening agent 26 in the mold 27 to 20% or less of the radius 32,as shown in FIG. 4. The reason is that if the hardening proceeds to theinner part and the thickness of the hardened layer 31 exceeds 20% of theradius 32, globing by a buoyant force during suspending in the hardeningagent 26 does not occur, and hardening of the gel portion is finished asit is left in the shape of the inner face of the mold 27 and as aresult, a spherical gel-coated seed 9 a cannot be obtained.

Thereupon, on the basis of reactivity of the hardening agent 26 upon thegelatinizer 30 and the permeability of the mold 27 to the hardeningagent 26, by selecting a raw material for the hardening agent 26 or anadditive to it, setting the concentration of the hardening agent 26, orsetting a time of immersing a gel-coated seed 9 a in the hardening agent26 until finally taking out the gel-coated seed 9 a from the hardeningtank 18, the thickness 34 of the hardened layer 31 is suppressed to 20%or less of the radius 32 of the semispherical portion 27 d of the mold27.

A raw material having such a gelatinizer impermeability or a slightgelatinizer impermeability, elasticity, a hardening agent permeabilityand retainability includes such fine porous materials as cloth ofnonwoven fabric and the like, paper, sponge and wire cloth, or porousresin, metal and ceramic, but is not limited in particular and may beany material having the characteristics described above. A raw materialhaving a shape memory ability in addition to the characteristics iseffective, and for example, when using a shape memory alloy transformingits shape according to a temperature change for the mold 27 and settingthe mold 27 so as to transform its bottom portion inward at a bathtemperature in the hardening tank instead of transforming by pressing, agel-coated seed 9 a is pressed out from the mold 27 in the hardeningtank 18 and after the mold 27 has come out from the hardening tank 18,the mold 27 is restored to its original shape due to an open-airtemperature, whereby it is possible to improve the mold releasabilitymore surely, moreover, without additionally installing new devices.

Hereupon, a first embodiment of a gel coating apparatus according to thepresent invention is described with reference to FIG. 5. The gel coatingapparatus comprises a mold 27, an object to be sealed feeding means 11,a gelatinizer feeding means 12, a mold immersing means 10, a hardeningtank 18 and a gel-coated object collecting means 13.

Among them, the object to be sealed feeding means 11 is composed of aseed hopper 28 accommodating a number of objects to be sealed such asseeds 9 and the like, a suction chip 29 detachably attached to the lowerface of an unshown arm supported turnably in a horizontal plane, and thelike, and the suction chip 29 is composed so as to be capable ofhorizontally going and returning above the seed hopper 28 and the mold27 being at an injection position 38. And the gelatinizer feeding means12 is composed of an unshown gelatinizer tank, a tube extending from thegelatinizer tank, a feeding nozzle 35 connected to the fore-end of thetube, and the like, and the feeding nozzle 35 is composed so as to becapable of horizontally going and returning to above the mold 27.

The mold immersing means 10 is composed of a swaying arm 36 coupled tothe mold 27 and the like, and the swaying arm 36 is swayed up and downby an unshown actuator between below the liquid surface of the hardeningtank 18 and the injection position 38 above the hardening tank 18.

The gel-coated object collecting means 13 is composed of two pulleys 19and 20 arranged in the longitudinal direction, a belt 24 wound aroundthe pulleys 19 and 20 and paddles 25, 25 and so on which are set uprighton the outer face of the belt 24. The paddles 25, 25 and so on are movedthrough the hardening tank 18 by rotation of the pulleys 19 and 20,generate a circulating flow 37 shown by an arrow in the figure, transfergel-coated seeds 9 a released from the mold 27 and suspending in theliquid surface, and scoop up them at the terminal and discharge them tothe outside. And in the hardening tank 18, a middle plate 18 a isprovided horizontally at a fixed height from a bottom plate 18 b, andstabilizes the circulating flow 37. In case of forming the mold 27 outof an elastic body as described above, the middle plate 18 a may be usedas a member for pressing up the bottom of the mold 27 immersed in thehardening agent 26 by the mold immersing means 10.

In a gel coating apparatus having such a composition, a gel coatingprocess can be performed by the following procedure. First, when themold 27 is at the injection position 38, the feeding nozzle 35 is movedto above the mold 27 and injects the gelatinizer 30 into the mold 27,and when the feeding nozzle 35 comes back to a specified position fromabove the mold 27, the suction chip 29 sucking and holding a seed 9 inthe seed hopper 28 is moved in turn to above the mold 27 and throws theseed 9 into the mold 27, and when the suction chip 29 comes back to itsspecified position, the feeding nozzle 35 is moved again to above themold 27 and injects the gelatinizer 30 into the mold 27.

The mold 27 having the gelatinizer 30 and the seed 9 injected into it islowered by the swaying arm 36 and immersed in the hardening agent 26,and the gel is hardened, and it is possible also to enhance the moldreleasability of a gel-coated seed 9 a by pressing the mold 27 againstthe upper face of the middle plate 18 a as occasion demands. When thegel-coated seed 9 a is raised through the hardening agent 26 by abuoyant force and pressing force, the mold 27 returns to the injectionposition. Gel-coated seeds 9 a generated by repeating the aboveprocedure are carried on the circulating flow 37 generated by paddles25, proceed in globing and hardening as being led by paddles 25, andgel-coated seeds 9 a which have reached the terminal are transferred tothe outside of the hardening tank 18.

Next, a second embodiment of a gel coating apparatus according to thepresent invention is described with reference to FIG. 6. The gel coatingapparatus comprises an object to be sealed feeding means 15, agelatinizer feeding means 16, a mold immersing means 14 having molds 27built in it, a hardening tank 18, and a gel-coated object collectingmeans 17.

Among them the object to be sealed feeding means 15 is, similarly to thefirst embodiment, composed of a seed hopper 28 accommodating a number ofobjects to be sealed such as seeds 9 and the like, a suction chip 29detachably attached to the lower face of an unshown arm supportedturnably in a horizontal plane, and the like, and the suction chip 29 iscomposed so as to be capable of horizontally going and returning abovethe seed hopper 28 and a waiting position 40, and so as to be capable ofswaying up and down between the waiting position 40 and a lower seedinjection position 41. And the gelatinizer feeding means 16 is composedof an unshown gelatinizer tank, a tube, a reserved feeding nozzle 42 aand a regular feeding nozzle 42 b which are connected to the fore-end ofthe tube, and the like, and the reserved feeding nozzle 42 a is disposedat a reserved injection position 43 in front of the seed injectionposition 41 and the regular feeding nozzle 42 b is disposed at a regularinjection position 44 at the back of the seed injection position 41.

The mold immersing means 14 is composed of an upper pulley 21 arrangednear the respective injection positions 41, 43 and 44 and near theliquid surface of the hardening agent in the hardening tank 18, a lowerpulley 22 arranged distantly from the upper pulley 21 and deeply fromthe liquid surface of the hardening agent, and a mold built-in belt 23which is wound around the lower pulley 22 and the upper pulley 21 andwhich has molds 27 embedded in it whose openings face outward. And thegel-coated object collecting means 17 is composed of a turning member 17a arranged above the liquid surface at the rear part of the hardeningtank 18, a plurality of blades 17 b, 17 b and so forth which areembedded in the outer circumferential face of the turning member 17 a,and the like, the gel-coated object collecting means 17 being capable ofscraping out gel-coated seeds 9 a released from the molds 27 to theoutside of the hardening tank 18.

In a gel coating apparatus having such a composition, a gel coatingprocess can be performed by the following procedure. First, the moldbuilt-in belt 23 is always turned by driving of the upper and lowerpulleys 21 and 22, and in case that a mold 27 built in the mold built-inbelt 23 is above the liquid surface, first the gelatinizer 30 isinjected into the mold 27 by the reserved feeding nozzle 42 a at thereserved injection position 43 and then at a point of time when the mold27 has arrived at the seed injection position 41, the suction chip 29sucking and holding a seed 9 in the seed hopper 28 lowers from thewaiting position 40 to the seed injection position 41 and throws theseed 9 into the mold 27, and further, at a point of time when the mold27 has come to the regular injection position 44, the gelatinizer 30 isinjected again into the mold 27 by the regular feeding nozzle 42 b.

The mold 27 having the gelatinizer 30 and the seed 9 injected into itsinks gradually into the hardening agent 26 with turning of the moldbuilt-in belt 23 and the gel is hardened in the hardening agent 26, anda gel-coated seed 9 a released from the mold 27 is raised through thehardening agent 36 by a buoyant force. Gel-coated seeds 9 a generated byrepeating the above procedure are carried on a flow generated by turningof the mold built-in belt 23 and, as being hardened, are transferred tothe outside of the hardening tank 18. Therefore, since the presentembodiment can consecutively perform a gel coating process, it issuitable for mass production, and it can optimize the hardeningconditions according to the size and shape of an object to be sealed andthe viscosity of a gelatinizer by adjusting a turning speed of the moldbuilt-in belt 23.

By arranging laterally a plurality of molds 27 of the first embodimentor a plurality of mold built-in belts 23 having molds 27 built in it ofthe second embodiment and arranging a plurality of corresponding objectto be sealed feeding means, gelatinizer feeding means and others, itbecomes possible to coat a number of objects to be sealed with gel at atime, and thereby it is possible to easily cope with mass production.

INDUSTRIAL APPLICABILITY

Such a gel coating method and apparatus as described above according tothe present invention can be applied to any object to be sealed having agrowth ability such as a seed, a cell piece having a germinating orrooting ability, or the like, and can be applied also to an object to besealed having any weight or an object to be sealed having anygerminating ability as a method and apparatus being capable of surelyperforming a gel coating process. And the present invention can providea spherical gel-coated object being excellent in mold releasability andprovide a gel coating method and apparatus having a reduced amount ofgelatinizer remaining in a mold.

What is claimed is:
 1. A gel coating method comprising the steps of:injecting a gelatinizer and an object to be sealed in a mold having botha gelatinizer impermeability or a slight gelatinizer impermeability anda hardening agent permeability; permeating the hardening agentthroughout the mold by immersing the mold in the hardening agent; andhardening the gelatinizer around said object to be sealed uniformly fromthe contacting part with the mold and thereby making it possible for theobject to be sealed to be easily released from the mold as a gel-coatedobject.
 2. The gel coating method according to claim 1, wherein as saidmold, a mold whose inner face is composed of a semispherical portionprojecting downward and a cylindrical portion set upright on thesemispherical portion and in which the whole depth from the top end ofthe cylindrical portion to the bottom end of the semispherical portionis made equal to or greater than the diameter of said semisphericalportion is used.
 3. The gel coating method according to claim 2, whereinas said mold, a mold whose inner face is composed of a semisphericalportion projecting downward and a cylindrical portion set upright on thesemispherical portion and in which the whole depth from the top end ofthe cylindrical portion to the bottom end of the semispherical portionis made equal to or greater than the diameter of said semisphericalportion is used.
 4. The gel coating method according to claim 2, whereinas said mold, a mold of a slight gelatinizer impermeability in which ittakes one or more seconds for a gelatinizer to permeate through the moldis used.
 5. The gel coating method according to claim 2, wherein as saidmold, a mold formed out of an elastic body which is transformed by beingpressed from its lower part and presses out a gel-coated object insidethe mold into the hardening agent and thereafter can be automaticallyrestored to its original shape is used.
 6. The gel coating methodaccording to claim 2, wherein the thickness of a hardened layer formedby reacting upon a hardening agent retained in advance in the mold whena gelatinizer is injected into said mold is limited to 20% or less ofthe radius of the semispherical portion forming the lower part of themold and projecting downward.
 7. The gel coating method according toclaim 1, wherein as said mold, a mold of a slight gelatinizerimpermeability in which it takes one or more seconds for a gelatinizerto permeate through the mold is used.
 8. The gel coating methodaccording to claim 1, wherein as said mold, a mold formed out of anelastic body which is transformed by being pressed from its lower partand presses out a gel-coated object inside the mold into the hardeningagent and thereafter can be automatically restored to its original shapeis used.
 9. A gel coating method comprising the steps of: immersing amold having both a gelatinizer impermeability or a slight gelatinizerimpermeability and a hardening agent permeability in a hardening agentand taking out the mold from the hardening agent in advance and therebyretaining the hardening agent in said mold; injecting a gelatinizer andan object to be sealed in the mold; permeating said hardening agentthroughout said mold by immersing the mold again in the hardening agent;and hardening the gelatinizer around the object to be sealed uniformlyfrom the contacting part with the mold and thereby making it possiblefor the object to be sealed to be easily released from the mold as agel-coated object.
 10. A gel coating apparatus comprising: a mold whichhas both a gelatinizer impermeability or a slight gelatinizerimpermeability and a hardening agent permeability; an object to besealed feeding means for throwing a specified number of objects to besealed into the mold; a gelatinizer feeding means for discharging anadequate amount of gelatinizer for applying to the object to be sealed;a hardening tank which is disposed below the gelatinizer feeding meansand said object to be sealed feeding means and is filled with ahardening agent; a mold immersing means which can consecutively immersethe molds in the hardening tank and take out the molds from the tank;and a gel-coated object collecting means for taking out a gel-coatedobject which is released from the mold and moves suspending in thehardening agent from the hardening tank, wherein the gel coatingapparatus immerses the mold having a gelatinizer and an object to besealed injected in it by the object to be sealed feeding means and thegelatinizer feeding means in a hardening agent inside the hardening tankby means of the mold immersing means and thereby makes the hardeningagent permeate throughout the mold to harden the surface of thegelatinizer in the mold and releases the gel-coated object from themold.
 11. The gel coating apparatus according to claim 10, wherein saidgel-coated object collecting means comprises two pulleys arranged in thelongitudinal direction, a belt wound around the pulleys, and a pluralityof paddles stood upright on the outer face of the belt, and the paddlesare moved through said hardening tank together with the belt by rotationof the pulleys, generate a circulating flow, transfer a gel-coatedobject suspending in the liquid surface, and scoop up and discharge agel-coated object transferred to the terminal to the outside.
 12. Thegel coating apparatus according to claim 10, wherein said mold immersingmeans comprises an upper pulley arranged near said gelatinizer feedingmeans and said object to be sealed feeding means and near the liquidsurface of the hardening agent in said hardening tank, a lower pulleyarranged distantly from the upper pulley and deeply in the hardeningagent, and a mold built-in belt wound around the upper and lowerpulleys, and the mold built-in belt has a plurality of molds whoseopenings face outward embedded in it.